Flexible follower for metal ampoules



Feb. 23, 1954 R. P. scHERER ErAL FLEXIBLE FOLLOWER FOR METAL AMFOULES Filed Ja n. 3l, 1951 umln .Il I! 'Il Patented Feb. 23, 1954 FLEXIBLE FOLLOWER FOR METAL AMPOULES- Robert. Pauli Scherer, Detroit, John Otto Scherer, Grosse .-Pointe,.and Leon V. Whipple, Berkley, Mich.,y assignors toy R. P. Scherer Corporation, Detroit, Mich., a corporation of Michigan Application'January 31, 1951, Serial No.`208,`676

2 Claims. .1.

This invention relates to a vstopper forvan :ampule for use in an injector for hypodermically injecting uid by the jet therapy method disclosedinthe copending Vapplication of Robert yRscherer, Serial No. 77,517,1iled February 21,

.19.49. The invention also relates to the combination of lsaidy stopper with an'ampule of the :type: indicated. An elementary form of hypo jet injector is disclosed in Va second copending applcationof .Robert'P..Scherer, Serial No. 94,579, `filed `May29, 19.49, while a more elaborate form of hypo jetinjector isl disclosed in .a third co- .pending application of Robert P. Scherer, Serial No. 170,101, led .June 24, 1950. The injectors :of said ycopending applications use -a hypo jet ampule of the type disclosedand claimed in a fourth copending'application of Robert P. Scherer.; SerialsNo. 93,282, led May 14, 1949.

One form of hypo jet injector disclosed in saidcopending Aapplications may be of generally elongated shape and may be provided at its lower 'end with an ampule holder lallowing one end of a. generally. tubular ampule toproject outside the holder for Contact with the skin when an invjection is fmade. This end of the ampule may beformed as. a more or less tapering nozzlehavingiat its top aminute discharge orifice. The uid to `be injected is kept within the 'ampule by a closure member. disposed in the open ampule end. "This closure member is not removed-when :thefampule is inserted into V the ampule Lholder forming kpart 'of the injector. In the operation ofthe injector, the closure member Ais `forcibly moved downwardly with-inthe ampule andwthus iacts ias a plunger-to eject Vthe `ampule contents lthrough the-minute dis-charge oriiice. More particuflarly; injection iseiected intwo stages. Tn 'the -rst 'stage injection is effected under high pressure, sometimes 'as high as 110,000 lbs-per square inch. In the secondstage, injection lis continuedfunder a pressure that, While reduced, 'still isrelatively `high, say, about 53,2000 lbs. per

'square inch. Both stagesof inecticn "are completed vwithin avery short yperiod of 'tima-'on the Iorder-'of a fraction-of 'a second. Further, the injector members operative'to eject thefampul-e content in such stages include aprimary plunger -slidable withiny a tubular seconda-ry plunger; Begfore the'injection, thesecondary plunger contacts the outer ymargin 'of vthe-'closure member to -hold vit against retrogradefmovemenu while the=prmary plungeris spaced from the center l.df-the. closure mem-ber. l'P-lungermovement .effected byy suddenly releasing energy "that may 'bestond-for instance, Ain springs.

(Cl. 12S-272) 2 Upon'release of the operating energy' thegprimary plunger alone is first driven `forward==a 4limited distance bythe `whole driving energy while the annular secondary .plunger is .held against'retrogrademotion. This causes'tlaec'enter portion of the bottom of a stopper constructed according to the .present invention 'tofbazdriw en inward, thereby being inverted and.tofa.fvery small measure stretched, as disclosed .ins'detail herein below. This initial actioncausesa: small reduction in the internal volumey of. thefam-pule which is `comparable to the veffect createdtbywa similar movement of a ysmall"diameter:piston and so produces the very high.hydraulicgzpressure involved in the primaryinjection.v

`Upon completion. of thisv Apre'elinfrinary "movement of the small primary: plunger onlythrough its predetermined lengthof initial travel', '.the driving mechanism, Iwithout stopping, alsoeengages the annular secondary plunger, whielzin the first stage was heldiagainst retrogrademiovement, land :advances vprimary and, :secondary plungers in unison. throughout the .fremainder of the injection. The net effect of thissiibsequent action isjthat. theeiectivespiston :diameter :has been increased to 'approximatelyfthreertimes thearea actedy on by primary plunger alone the result that the hydraulicfpressurefis reduced :to-about one-third ofthat produced bytheprimary plunger alone,`while'the volume 'ofnn'id moved through the orice per .unit length fro'f plunger travel is nowa'boutu three .timesfasflgreat as in the primarystag-e.

Said. copending application, Serial No. 93,282, relates, inter alia, to.y the configuration offthe "discharge end of the ampule. The presentfappli- :cationrelates particularly tothe saidstop'perfor .closure member, as Wellas'to .the combination therewith kof 'the said tubular ampule.

Thecl'osure member vof the prf-:sent4 invention is characterized by a number of features-faidapt- `ingthesame for use in an injector of' tlretype indicated. The Vclosure rmember is made `loferesilient material such as rubber. kThe closure 'member vis generally cup-shaped and 'has `-its mouth facing the discharge orifice. VlFurther,the A'stopper is provided with yside walls or' otherparts depending from the stopper bottom whichrare tapered or otherwise so formed as to conform, Vat .the end of the plunger stroke, 'withftheinrior contour of the discharge end 'ofthe ample to effectl complete expulsion ofthe ampulecontents `without 'unduly'stressing thegfamplilewalls The bottom of the lclosure member'isformed'fso as ftof-"be invertible atlthe beginningo'fthep'- mary plunger stroke, as by having an annular groove on its outside, the bottom being thinner within this groove than the side walls.

It is therefore an important object of the present invention to provide, for use in a jet injector of the type indicated, an ampule having a closure member particularly adapted to cooperate with said jet injector to eject the capsule content completely within a brief period of time under a pressure that is initially high but is thereafter reduced.

Another important object of this invention is to provide a cup-shaped ampule closure member characterized by the above disclosed features and adapted for use, in combination with the ampule of said copending application, Serial No. 93,282, in a jet injector of the type indicated.

Other and further objects and features of this invention will become apparent from the following description and appended claims as illustrated by the accompanying drawings which show, by way of examples, an ampule according to this invention and a hypo jet injector. More particularly:

Figure 1 is a cross sectional view taken along the line l-l of Figure 2;

Figure 2 is a plan view of a closure member for an ampule;

Figure 3 is a bottom plan view of the closure member of Figure 1;

Figure 4 is a longitudinal cross sectional View of an ampule including` the closure member of Figures 1 to 3, with part of the closure member shown in elevation;

Figure 5 is a fragmentary longitudinal, cross sectional view through a hypo injector having inserted therein the ampule of Figure 4 and showing the injector with its parts in the positions assumed immediately before an injection is initiated;

Figure 6 is a view similar to that of Figure 5 but showing the parts in positions assumed during the initial or high pressure stage of the injection;

Figure 7 is a view similar to that of Figure 5 but showing the parts in positions assumed in the early part of the second or low pressure stage of the injection; and

Figure 8 is a View similar to that of Figure 5 but showing the parts in the positions assumed as the injection is terminated.

The injector shown in the drawings is identical with that shown in said copending application of Robert P. Scherer, Serial No. 170,101, and the same numerals are used in this application as in said copending application, whenever referring to corresponding parts, to facilitate cross reference to said copending application. For a complete description of said injector and its operation, reference is made to said copending application.

Referring now to Figure 4, there is shown a generally tubular metal ampule 'Il formed with a reduced discharge nozzle 'M perforated -by a discharge orice I5 of capillary size having, for instance, a diameter of from 0.002 to 0.010 inch. I'he ampule is filled with medicament 12 and is closgd by a cup-like follower generally indicated at The cup-like follower 13 is best illustrated in Figures 1 to 3. As shown, the follower is formed with a side wall 'i3d and a bottom having an outside groove '13b extending inside the side wall 13a. Otherwise, the outer surface of the follower bottom lies in one plane. The bottom portion outside the side wall 73 is designated by the reference numeral IEC, while the central bottom portion inside the groeve 'ib is designated by the reference numeral i3d. This central bottom portion i3d is of inverted U-shaped cross sectional form and has a thickness about one-half of the side wall 13a. The bottom portion 'ic outside the groove 13b has an axial thickness about equal to the depth of the groove '13b plus the thickness of the central bottom portion ld. Further, the outside of the groove lh is spaced from the inside of the side wall '13a by the thickness of the legs of the U-shaped bottom portion i3d so that on inversion thereof these legs will abut against the inside of the side wall 73a without stretching.

The side wall 13a diverges from the longitudinal axis of the follower by about 3. rl'he lip of the follower is formed with an outer plane narrow annular surface '36 extending at a right angle to said longitudinal axis and with an inner annular surface 73j diverging from said longitudinal axis by from 25 to 35 or 45, say, about 30 or 40.

In Figures 5 to 8 there is shown an injector including a dosage sleeve 3B externally threaded at its end to receive an ampule holder l0. These two members jointly dene an elongated cylindrical chamber adapted to receive and support an ampule 7|. A flexible non-slip nose l of rubber or similar material such as neoprene covers the ampule holder It. The reduced nozzle 'irl of the ampule Il projects through a suitable aperture in the ampule holder 'E0 and nose it so that the tip of the nozzle le can directly Contact the skin through which the medicament 'l2 is to be injected.

The injector further comprises means for ejecting the capsule contents 'i2 such as a primary plunger Bil of smaller diameter than the ampule il and a secondary plunger made up of an upper disc-like portion 92 and, projecting therefrom, a sleeve-like portion 9| slidingly fitting around the primary plunger 85 and adapted to nt slidingly inside the ampule ll. Vents 33 are provided in the dosage sleeve Si) terminating in a relieved annular space 34 between the dosage sleeve SB and the ampule holder 10, for the purpose of discharging air displaced downwardly on movement of the secondary plunger.

The ampule 1l is initially received and supported in the injector in the manner shown in Figure 5, the end of the primary plunger being spaced slightly from the follower or closure member 'I3 and the leading edge of the secondary plunger sleeve 9i resting upon the margin 13e of the bottom of the closure member I3. In the operation of the injector, the end of the primary plunger first engages the central bottom portion 13d of the closure member 13 with an impact blow and thereafter moves further downward so as to invert and at most slightly stretch the bottom portion '13d of the closure member, as shown in Figure 6. During this time, the secondary plunger sleeve Bl remains stationary. This period of time represents the first or high pressure stage of the injection, during which the side wall l3a of the closure member remains practically stationary. The movement of the primary plunger 8l) is quite rapid to build up the initial high pressure, and in fact so rapid as to preclude bodily movement by the closure member under the pressure exerted by the primary plunger. Instead, the central bottom portion 13d of the closure member is inverted.

Next, as shown in Figure '7, the primary fpiunger-isc centimes #its --feownwara immersa =and `the seeondaryfplunger l#sleeve 139111v likewise moves fdownwardly, A#se 4tliiat' ithesclosureimeriiber closure member has entered thefaseducedsample .nozzle 1A. Due to the divergence of the annularlip surface 13j, medicamentcan sti-llfescape therebetween until the last.. moment. sotbat no .medicament is dammed up or-.trapped-'witliin the ampule. The last drop tof .fmedicameritis squeezed out between the stretched bottom Y"13d of the closure member and the side wall 13a and between the opposed parts of the surface 13j. Note, in this connection, that the secondary plunger sleeve 9| does not descend as far as the primary plunger 80 and that the tapering form of the closure member lip aids in preventing curling up of the latter when confined in the reduced ampule nozzle 14.

As discussed hereinabove, a number of structural features of our flexible stopper or follower contribute to the cooperation between the stopper and the ampule in effecting a rapid complete two stage injection of the ampule contents. ward flare of the stopper side wall which assures sealing contact of the stopper side wall with the inside of the ampule. The axial length of the stopper side wall may be varied so as to assure good sealing contact Without excessive frictional resistance to stopper movement within the metal ampule which would follow from the use of a stopper side Wall of too great axial length. At the same time, the stopper side wall is made long enough to insure good sealing contact. It will be understood that the materials of construction of the stopper and of the metal ampule, as well as the greater or lesser smoothness of the contacting stopper and ampule surfaces, are among the factors which must be considered in determining the axial length of the stopper side Wall.

Another important feature of our stopper is the tapering terminal shape of the stopper side wall which permits the side wall to enter the tapering discharge nozzle of the ampule with out obstructing discharge from the nozzle.

A further important feature of our stopper is the shape of the stopper bottom which in normal or relaxed position presents essentially flat surfaces to the injector plungers while the central bottom portion is inversible or inwardly deformable with little or no stretching, in the manner of an inversible diaphragm. Thus, the internal volume of the ampule may be suddenly reduced to an appreciable extent without much, if any, stretching of the stopper material. For this purpose, the margin of the central inversible bottom portion must be thin enough to permit flexing and should be normally directed upwardly for downward flexing upon initiation of injection. Inside this margin, the stopper bottom may be thicker.

A further important feature is the spacing from the stopper side wall and the thickness of the These features include the slight out- '.Sbottom.' ""Note I-thatroxrttnvera the centra opperibottomiportloh'aa'outs *fithei'stopper1siderwlltoisqueezer outzampule'sconitents But nih-e .iinvertedsstopper@bottom .':do'es inottherebwsubjectithe istepp eriside'iwall .to'z'addirtifcnal' pressure, zas would @be :the cease, ifor :finistancegfif :thenverted steppertbottom .would be Ithicker .fthesspace .'ileft available rfbetween atheestopper:Isetwallaandthe primary plunger stutter ithesprimarynplunger elias .r.;descended far 'zenongh to rzefectgzirrversionuaof @the stopper .':bot-

fatemi.. i

Another".imnortautzvfeature: is :the fetctal cross -ssectonal :iarearof `rtl'ier.inverted stopper which yis fcontaolledfso-las-itospermit entryyo'fthe lower -end portionf.\id1tc f the tapering :discharge rend without obstructing room-plete discharge .of :the fampsule .contents .but .at theisame timemsubstantially..fillthe discharge endof` theearnfpule.to'finsure complete discharge of fthe; ampule contents 4Note xthatscomplete.dischargefisvsecured with'flit- ,.tle, vi-f -aly.,vrstretchingl 'of .-thef' stopper material.

The resilient material makinkg up the closure member. 13 should be capable of at least 500% elongation. Its tensile strength is suitably regulated so as to fall within the range of from 1500 to 3000, and preferably from 2000 to 3000 lbs. per square inch. Compressibility is preferably regulated to fall within the range of from 60 to 70 Shore A as measured using the Shore hardness durometer type A.

The frictional resistance against follower movement with the capsule depends of course upon the nature of the resilient material of which the follower'is made, upon the nature of the metal of which the ampule is made and upon the smoothness of the contacting surfaces. The ampule is suitably made of the alloy disclosed and claimed in the copending application of Leon V. Whipple, et al., Serial No. 93,286, led May 14, 1949, entitled Alloy and Container Made Therefrom. When the ampule is made from the alloy of said copending application, the closure member may be made of a composition tabulated as h follows:

Ingredient Pagg by Butadiene-acrylonitrile copolymer (76:24) 100 Carbon blac 50-70 Zinc oxide (C. P.) 3-6 Stearic acid (quadruple pressed, triple distilled) %-l% Parati-ln wax (in P 132 C.) l-7 White mineral oil (U. S. P. 3-10 Vulcanizing agent (E. G. hyl thiuram disulde). l-3

The tabulated composition may be cured at 312 F. for from about 5 to 30 minutes. A curing period of 10 minutes is preferred.

Any suitable natural or synthetic rubber or the like can be used. When other gum stocks are used than the specific nitrile rubber disclosed, the other ingredients may be used in other proportions. The stearic acid, paraffin wax and mineral oil'are added in-amounts sufficient to prevent rubber to metal adhesion, butnot enough to be liberated from the rubber, as on storage or on subjection to pressure.

Many details of structure and composition may be varied without departing from the principles of this invention. It is therefore not our purpose to limit the patent granted on this invention otherwise than necessitated by the scope of the appended claims.`

We claim:

1. In a jet injection ampule, a tubular shell serving as a medicament container and having one end tapered and closed except for a minute ejection orice, the other end being open, and a resilient generally cup-shaped closure member for said open shell and disposed therein with its mouth facing said closed ampule end, the bottom of said closure member being formed with an inner central recess and with an outer axially extending annular groove surrounding said recess permitting axial movement of the recessed bottom portion, the side wall of said closure member being of uniform thickness, inclined outwardly with respect to the longitudinal axis of said closure member, and being formed with an outwardly cylindrical lip bounded terminally by an inner outwardly inclined annular surface.

2. A resilient generally cup-shaped imperforate closure and plunger member for a tubular ampule, said closure member having a bottom and side Wall, said side wall being of uniform thickness, inclined outwardly, and formed with an outwardly cylindrical lip bounded terminally by an inner outwardly inclined annular surface, the

bottom of said closure member having a central recess in its inner side and formed with an outer axially extending annular groove inside said side wall and permitting axial exing of said recessed bottom portion.

ROBERT PAULI SCI-IERER. JOHN OTTO SCHERER. LEON V. WHIPPLE.

References Cited in the le of this patent UNITED STATES PATENTS 

